Reclusive North Korean leader Kim Jong-il has promoted his youngest son, Kim Jong-un, to the rank of general, just one day before a rare meeting of North Korea's ruling Workers Party. The move added to speculation that Kim Jong-un will take over for his ailing father in the future.

We speak with Charles Armstrong, the director of the Center for Korean Research at Columbia University, about what that succession could mean for the secretive authoritarian state with nuclear ambitions, and for the rest of the world. We also go to Seoul to get the latest from the BBC's John Sudworth and, later, Mark McDonald of The New York Times.